The major pheromone-inducible protein, PD78, believed to contribute to bacterial conjugation, was purified from Enterococcus (formerly Streptococcus) faecalis cells containing the plasmid pPD1. A cloned EcoRI-Bg/II 3.6-kbp fragment of the plasmid pAM351 (pPD1::Tn916) contained an open reading frame corresponding to 467 amino acid residues representing PD78. In a central region of the deduced protein, there is a repeated sequence of X-X-Pro that is repeated 15 times. This is analogous to the Gln-Gln-Pro repeat in the C-terminal region of TraD product encoded on the R 100 plasmid in Escherichia coli.
